[seqfan] Re: More fractal triangles

Eric Angelini Eric.Angelini at kntv.be
Tue Jan 13 23:16:48 CET 2015


Again, Reinhard, thank you so much!
Those regular/irregular trees are beautiful!
Best,
É.
Catapulté de mon aPhone

> Le 13 janv. 2015 à 19:37, "Reinhard Zumkeller" <reinhard.zumkeller at gmail.com> a écrit :
> 
> see https://oeis.org/A249484
> 
> best, R.
> 
> 2015-01-12 17:19 GMT+01:00 Eric Angelini <Eric.Angelini at kntv.be>:
> 
>> Hello SeqFans,
>> Erase from S all pairs of integer [a(i), a(i+1)] having the
>> same parity --like (2,4) or (3,5)-- and you'll get S back.
>> 
>> S =
>> 1,2,4,3,5,2,7,9,4,3,6,8,5,2,7,10,12,9,4,3,6,11,13,8,5,2,7,10,15,17,12,9,4,3,6,11,14,16,13,8,5,2,7,10,15,18,20,17,12,9,4,3,6,11,14,19,21,16,13,8,5,2,7,10,15,18,23,25,20,17,12,9,4,3,6,11,14,19,22,24,21,16,13,8,5,2,7,10,15,18,23,26,28,25,20,17,12,9,4,3,6,11,14,19,22,27,29,...
>> 
>> 
>> The generating triangles [after a(1)=1] are:
>> 
>> 1            2                                4,3
>>           5,2,7                            9,4,3,6
>>         8,5,2,7,10                      12,9,4,3,6,11
>>      13,8,5,2,7,10,15                17,12,9,4,3,6,11,14
>>   16,13,8,5,2,7,10,15,18          20,17,12,9,4,3,6,11,14,19
>> 21,16,13,8,5,2,7,10,15,18,23    25,20,17,12,9,4,3,6,11,14,19,22
>>            ...                               ...
>> 
>> Read horizontally, line after line, to see S.
>> Best,
>> É.
>> 
>> 
>> _______________________________________________
>> 
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> 
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